Remove existing duplicate config lines when saving config

SaveConfig previously rewrote every config line whose option name
matched a save request entry, so duplicate lines accumulated by
earlier versions (issue #588) were preserved forever even though new
appends were prevented. Write each option only once in the replacement
path as well, so a single save converges a damaged config back to one
line per option. Add a regression test covering exact and case-variant
duplicate lines.

Author: xbmc4lyfe

daemon/extension/ScriptConfig.cpp

@@ -118,7 +118,9 @@ bool ScriptConfig::SaveConfig(Options::OptEntries* optEntries)
 			if (g_Options->SplitOptionString(buf, optname, optvalue))
 			{
 				Options::OptEntry* optEntry = optEntries->FindOption(optname);
-				if (optEntry)
+				// write each option only once, dropping duplicate lines accumulated
+				// in the config file by earlier versions (issue #588)
+				if (optEntry && writtenOptions.find(optEntry->GetName()) == writtenOptions.end())
 				{
 					infile.Print("%s=%s\n", optEntry->GetName(), optEntry->GetValue());
 					writtenOptions.insert(optEntry->GetName());

tests/extension/ScriptConfig.cpp

@@ -78,4 +78,42 @@ BOOST_AUTO_TEST_CASE(SaveConfigDoesNotAppendDuplicateOptionNames)
 	BOOST_CHECK_EQUAL(secondContents, firstContents);
 }
 
+BOOST_AUTO_TEST_CASE(SaveConfigRemovesDuplicateLinesFromDamagedConfig)
+{
+	TempConfigFile configFile;
+	{
+		std::ofstream output(configFile.path);
+		output << "# existing config\n"
+			<< "Server1.Active=yes\n"
+			<< "Server2.Active=yes\n"
+			<< "Server2.Active=yes\n"
+			<< "server2.active=yes\n"
+			<< "Server2.Host=news.example.com\n";
+	}
+
+	OptionsGuard optionsGuard;
+	Options options("nzbget", configFile.path.string().c_str(), true, nullptr, nullptr);
+	g_Options = &options;
+
+	Options::OptEntries optEntries;
+	optEntries.emplace_back("Server1.Active", "yes");
+	optEntries.emplace_back("Server2.Active", "no");
+	optEntries.emplace_back("Server2.Host", "news.example.com");
+	ScriptConfig scriptConfig;
+
+	BOOST_REQUIRE(scriptConfig.SaveConfig(&optEntries));
+	std::string contents;
+	{
+		std::ifstream file(configFile.path);
+		std::stringstream buffer;
+		buffer << file.rdbuf();
+		contents = buffer.str();
+	}
+	BOOST_CHECK_EQUAL(contents,
+		"# existing config\n"
+		"Server1.Active=yes\n"
+		"Server2.Active=no\n"
+		"Server2.Host=news.example.com\n");
+}
+
 BOOST_AUTO_TEST_SUITE_END()